The National Cancer Institute seeks to reduce the nation's cancer mortality by 50% by the Year 2000. Studies have demonstrated the effect of smoking and dietary habits on the incidence of cancer, and the benefits of screening for early detection of cancer. Yet, few primary care physicians counsel or screen the majority of patients. Educational interventions have had mixed success in improving the use of screening and counseling; various reminder systems to change physician and patient behavior have shown promise. Most studies, however, have been conducted in university-based clinics or health maintenance organizations. The proposed study would test a multifaceted intervention, including computerized reminders to physicians and patients, as well as professional and patient education. Selection of these strategies is based upon our findings of their potential to alter physician and patient behavior. The study is a three-year randomized, controlled trial in the private office practices of 40 primary care physicians in Northern California. Over two years, three cohorts of physicians will be randomly assigned to the control or intervention groups. Baseline data about counseling and screening performance will be collected from patient medical records and telephone interviews; baseline knowledge and attitudes of physicians will be assessed by written questionnaires. During one- year intervention periods, a computerized Cancer Prevention Reminder System will be introduced in the experimental physicians' offices, and educational materials distributed. During the post-intervention period, repeat measurements of counseling and screening performance will be compared to pre-intervention measurements. Targeted dependent variables will be two counseling activities (smoking and diet counseling) and seven screening activities (stool occult blood test, rectal examination, sigmoidoscopy, Pap smear, pelvis examination, breast examination and mammography). Data will be analyzed by analysis of variance and regression techniques. The long-term goal of this project is to increase performance of cancer prevention activities and to enhance the discovery of cancer at early, more treatable stages. Specific steps toward this goal include: 1) assessment of the effectiveness of the intervention in promoting cancer prevention activities; 2) evaluation of the feasibility of implementing the intervention in the office practice setting; and 3) dissemination of our findings and program to physicians in other settings to assist them in establishing their own cancer prevention programs.